Heat sink

1. A cold forged aluminum heat sink including a base portion, said base portion includes a first surface for thermally coupling said heat sink with an electronic device, and a second surface on which a first and a second group of heat dissipating members are integrally formed and extend upwardly therefrom; said first group of heat dissipation members includes a plurality of fin-shaped members each having main heat dissipation surfaces surrounded by thin peripheral edges including a top edge, an inside edge and an outside edge, said thin peripheral top edges generally extend from the interior of said base portion towards the outside periphery of said base portion, said main heat dissipation surfaces on adjacent heat dissipation members are substantially opposing to each other, and said second group of heat dissipation members are disposed between said first group of heat dissipation members and the center of said base portion.

2. The heat sink of claim 1 wherein said second group of heat dissipation members includes a plurality of curved fin-shaped members.

3. The heat sink according to claim 2 wherein said second group fin-shaped members includes main heat dissipation surfaces interconnected by a thin peripheral top edge, said peripheral edge extends generally from said center to the exterior of said base portion and have a thickness substantially thinner than that of said first surface said base portion.

4. The heat sink of claim 1 wherein the inside and outside thin peripheral edges of said first group heat dissipation members are respectively disposed on two concentrated circles.

5. The heat sink of claim 1 wherein the heat dissipation members of said first group are disposed in a generally annular member with the fin-shaped manner disposed in a substantially radial manner.

6. The heat sink of claim 1 wherein the outside thin edge of the first group of fin members is thinner than the inside edge of the fin members.

7. The heat sink of claim 2 wherein the curved fin-shaped members are generally disposed so that the adjacent curved fin-shaped members have generally similar curvation and length and are disposed in generally the same direction.

8. The heat sink of claim 7 wherein the ratios between the maximum height of fins in the first group of heat dissipating members to that of the second group of heat dissipating members are in a range from 2.1 to 6.7.

9. The heat sink of claim 1 wherein the second group of heat dissipating members includes fin-shaped members which are substantially shorter than the fin-shaped members of the first group of heat dissipating members and at least less than 51% shorter than the height of the first group of heat dissipating members.

10. The heat sink of claim 1 wherein at least some of the first group of heat dissipating members are fin-shaped with a zigzag outline so that the upmost end of said zigzagged member overhangs the base of said zigzag member.

11. A cold forged aluminum heat sink including a base portion, said base portion includes a neck portion and a shoulder portion, said shoulder portion abuts said neck portion and has a substantially larger cross-sectional area than said base portion wherein a plurality of heat dissipating heat members are integrally formed along the periphery of said shoulder portion so that said fin members are substantially overhanging said shoulder portion with space separating the adjacent fin members defining a plurality of cooling-air channels, said neck portion being of higher density than the shoulder portion.

12. The heat sink of claim 10 wherein said shoulder portion is adapted to extend beyond and overhang the package of an electronic device.